Clinicopathological study of 30 Cases of Cutaneous Mastocytosis

Background : Mastocytosis is characterized by accumulation of mast cells in various organs, most frequently, in skin. Cutaneous mastocytosis is a relatively rare disease in outpatient clinics and the clinicopathological study has not been done yet in Korea. Objective : The aim of this study is to analyze the clinicopathological features of cutaneous mastocytosis. In addition, we examined CD117 expression in the skin biopsy specimens immunohistochemically. Methods : Thirty cases of cutaneous mastocytosis were collected from 1990 to 1999 in Asan Medical Center. Clinical records, photographs, and biopsy slides were reviewed. In each biopsy specimen, CD117 was stained by immunoperoxidase method. Results : Among 30 cases, 29 cases were childhood type urticaria pigmentosa(76.7%) or mastocytoma(20.0%) and only 1 case occurred after 16 years of age. The incidence showed a peak under 1 year old (70.0%) and males affected 2.3 times as much as females. The trunk and distal extremities are the most common site of urticaria pigmentosa and mastocytoma, respectively. CD117 was strongly positive in all cases of urticaria pigmentosa (both child and adult type) and mastocytoma. Conclusion : Urticaria pigmentosa of infantile onset was the most common, followed by infantile mastocytoma. Systemic reactive manifestations arc rare in cutaneous mastocytosis. The strong expression of CD117 was seen regardless of the type of cutaneous mastocytosis.